JPH09320603A - Manufacture of pulverized active material for lithium secondary battery - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for manufacturing a pulverized active material for use in a lithium secondary battery, that is made from a spinel or stratified type lithium-containing oxide which has a uniform composition, has a small particle diameter, does not cause oxygen loss, and undergoes almost no capacity deterioration even in the case of repeated charge and discharge at high current density. SOLUTION: A suspension 1 in which the raw material of a pulverized active material is suspended in a combustible liquid, or an emulsion in which a solution of the raw material is emulsified in a combustible liquid, is sprayed in the form of droplets 15, along with an oxygen-containing gas 2, and the combustible liquid in the droplets 15 is burned. The raw material in the droplets is thereby reacted and the solvent is evaporated to manufacture pulverized active material 4 of a spinel type lithium-containing oxide. Also, oxide powders are obtained by spraying and heating of the droplets, and are reheated to obtain pulverized active material of a stratified lithium-containing oxide.

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a method for producing a powdery active material used for a positive electrode or a negative electrode in a lithium secondary battery using a non-aqueous electrolyte.

[0002]

2. Description of the Related Art Among various secondary batteries, lithium secondary batteries, in particular, have high voltage, low self-discharge, and excellent storage stability. Therefore, it is expected as a promising secondary battery in many fields. As a lithium secondary battery,
LiCoO ₂ , LiNiO ₂ , LiMn ₂ may be used as the positive electrode active material.
There is one that uses a metal oxide such as O ₄ and a negative electrode active material such as lithium metal, a lithium alloy, or a carbon body capable of absorbing and desorbing lithium ions (JP-A-63-1).
14065).

By the way, the above-mentioned active materials are conventionally powders of lithium raw materials such as Li (lithium) metal, oxides of Li, hydroxides and carbonates, and metals such as Mn, Ni and Co, or oxides thereof. It was manufactured by a solid-phase reaction method in which powders such as hydroxide and carbonate were mixed and heated at a high temperature for a long time.

[0004]

However, the above-mentioned conventional method for producing an active material by the solid-phase reaction method requires a high temperature and a long time. Further, since the above-mentioned conventional active material is a solid-phase reaction, the active material raw material does not react sufficiently, and an active material having a uniform composition cannot be obtained. The obtained active material has a large average particle diameter of 10 μm to 20 μm. Further, in a lithium secondary battery using the above active material, the capacity deterioration is large when charging and discharging at high current density.

Further, as a method for producing a powdery active material for a lithium secondary battery, which has a uniform composition, a small particle size, and a small capacity deterioration even when charged and discharged at a high current density, A raw material obtained by dissolving the raw material for the active material in a solvent is sprayed in a droplet shape, and then the droplet is heated to
There is a spray pyrolysis method in which the above-mentioned solvent therein is evaporated to obtain a powdery active material (JP-A-2-9722).

However, in the above-mentioned conventional spray pyrolysis method, even if the heating method is the external heating method or the internal heating method, a temperature distribution is generated in the heating portion, so that the uniformity of the composition is often not obtained. In particular, when producing a complex oxide of substances having different vapor pressures, the composition tends to be non-uniform. In addition, if there is a temperature distribution, even if the optimum temperature conditions for oxide formation are set, the temperature may be too high or too low depending on the location, so it cannot be controlled when the raw material contains volatile components. .

Although not a method for producing a powdered active material for a lithium secondary battery, a method is proposed which can produce a composite oxide powder having a uniform temperature distribution and a small temperature distribution in the heating part. ing. In this method, a suspension in which a substance that becomes an oxide when oxidized is suspended in a flammable liquid, or a solution in which a substance that becomes an oxide when oxidized is dissolved in a liquid is placed in a flammable liquid. This is a combustion spray pyrolysis method in which one or both of emulsified emulsions are sprayed and heated in an oxidizing atmosphere (JP-A-7-81905).

However, in the combustion spray pyrolysis method, a large amount of oxygen is consumed when the combustible liquid burns.
Therefore, if a composite oxide having a spinel structure is synthesized by the above-mentioned combustion spray pyrolysis method, only powder with many oxygen deficiencies can be obtained.

In particular, spinel type lithium-containing oxides such as LiMn ₂ O ₄ have distortions in the crystal structure when oxygen is deficient, and when used as a powdery active material for a lithium secondary battery, they are repeatedly charged. Large capacity deterioration due to discharge.

In view of such conventional problems, the present invention has a uniform composition, a small particle size, no oxygen deficiency, and almost no capacity deterioration even during repeated charge / discharge at high current density. An object of the present invention is to provide a method for producing a powdery active material for a lithium secondary battery, which method comprises a spinel-type or layer-type lithium-containing oxide.

[0011]

According to a first aspect of the present invention, there is provided a method for producing a powdery active material for a lithium secondary battery, the suspension comprising a raw material of the powdery active material suspended in a flammable liquid, Alternatively, an emulsion prepared by emulsifying a solution of the raw material of the above powdery active material in a solvent in a flammable liquid,
The droplets are sprayed in an atmosphere containing oxygen, and then the flammable liquid in the droplets is burned to heat-treat the droplets to react the raw materials in the droplets, A method for producing a powdery active material for a lithium secondary battery, which comprises producing a powdery active material made of a spinel-type lithium-containing oxide (hereinafter referred to as a first invention).

The most remarkable point in the first invention is
The raw material of the powdery active material in the form of suspension or emulsion is sprayed into droplets in an atmosphere containing oxygen, and the flammable liquid is burned to heat the droplets to react the raw materials. To obtain a powdery active material composed of a spinel-type lithium-containing oxide. That is, the present invention supplements the shortage of oxygen during the combustion by spraying the droplets in an atmosphere containing oxygen,
It promotes the above reaction.

The flammable liquid serves as a suspension or emulsion medium, and uses one or more of light oil, heavy oil, kerosene, gasoline and the like. When the raw material of the powdered active material is emulsified in a flammable liquid, it is preferable to add an emulsifier or stir with a homomixer or the like. As the emulsifier, one that does not contain metal ions is desirable, and it is particularly desirable to use a nonionic surfactant.

When an emulsion is prepared, a suitable emulsifier such as sorbitan monolaurate is used to obtain an emulsion in which spherical particles having a substantially uniform diameter are dispersed. The uniformity of the diameter of the dispersed spheres is reflected in the particle diameter of the obtained powdery active material. According to the present invention, as described above, it is easy to prepare an emulsion in which the diameter of dispersed spheres is uniform. Therefore, it is easy to manufacture a powdery active material having a uniform particle size. In addition, as an emulsion, a solution in which the above raw material is dissolved in a solvent in a flammable liquid is emulsified, and the above raw material is suspended in the above flammable liquid, that is, one in which an emulsion state and a suspension state coexist. Can be used.

As a method of spraying the suspension or emulsion, a method of spraying with a gas containing oxygen,
Alternatively, there is a method of spraying the suspension or emulsion in an atmosphere (gas) in which oxygen exists. Among them, the method of spraying with the oxygen-containing gas is preferable because the reaction efficiency is higher. As a method of spraying with this oxygen-containing gas, a sprayer (atomizer) using compressed air is used.
In addition, a method of supplying a suspension or emulsion by a metering pump and spraying it into the reactor can be mentioned.
The higher the spray amount, the better the production efficiency, but the oxygen partial pressure in the reactor may decrease, and the combustion temperature may become too high. Therefore, the amount of spray should be determined in consideration of these points.

In the present invention, the suspension or emulsion is sprayed into the reactor in an atmosphere containing oxygen, and the flammable liquid in the suspension or emulsion is burned at that time. As the combustion method, the sprayed droplets are heated by a burner or the like. Alternatively, the spray droplets are passed through a flame or a portion heated to a high temperature. A pilot burner should be used to support stable combustion and facilitate ignition.

As an atmosphere for heating, an oxidizing atmosphere is required in order to prevent oxygen deficiency in the powdery active material as described above. Therefore, as described above, the droplets are sprayed in the atmosphere containing oxygen. The oxygen partial pressure in the reactor during the heat treatment is preferably controlled so that the oxygen partial pressure is 20% or more, assuming that the combustible liquid is completely combusted.

For example, when a suspension or emulsion is sprayed with an oxygen-containing gas, a spinel-type lithium-containing oxide without oxygen deficiency can be synthesized by controlling the amount of oxygen-containing gas so that the oxygen partial pressure becomes such. , It can be used as a powdery active material for lithium secondary batteries. The upper limit of the oxygen partial pressure is preferably 95% or less in consideration of the amount of oxygen consumed by the combustion of combustible liquid such as kerosene. The oxygen-containing gas for forming the oxidizing atmosphere is, for example, air, nitrogen gas, or a mixed gas of air and oxygen.

The produced powdery active material is collected so as not to scatter. Further, exhaust gas containing water vapor is generated by combustion at the same time as the generation of the powdery active material. for that reason,
In particular, the water vapor may wet the powdery active material. Therefore, it is advisable to collect the powdered active material during high temperature and separate it from the exhaust gas. For example, in order to collect only the powdery active material, a filter such as punching metal may be used, and only the powdery active material that has passed through may be deposited and collected (see the embodiment example).

Next, the operation of the present invention will be described. In the present invention, the above raw materials are mixed in the liquid state of suspension or emulsion. Therefore, the raw material can be completely homogenized. Since the homogenized droplets are sprayed and heated, the composition of the obtained powdery active material does not lose uniformity.

That is, the raw material instantly reacts with the heat of the heat treatment in the droplet to become an active material. On the other hand, when an emulsion is used, the solvent in the droplets evaporates as an unnecessary portion due to the heat during the heat treatment and is released to the outside of the reaction system. Therefore, the active material can have a uniform composition.

Further, the individual active material particles are individually formed for each of the droplets sprayed as described above. for that reason,
The active material is obtained as a powdery active material composed of primary particles of fine particles or secondary particles in which these particles are bonded (see FIG. 4). Further, the fine particles generated from the sprayed droplets have an average particle diameter of 0.01 to 10 μm.

Further, in the present invention, the heat treatment of the droplets is performed by burning a combustible liquid, and the droplet spraying is performed in an atmosphere containing oxygen.
Therefore, in the obtained spinel-type lithium-containing oxide, oxygen deficiency does not occur, and an excellent powdery active material can be obtained. Thus, the reason why oxygen deficiency does not occur is presumed to be as follows. That is, the oxygen deficiency of the spinel-type lithium-containing oxide is a function of temperature and oxygen partial pressure, and the higher the temperature and the lower the oxygen partial pressure, the more likely oxygen deficiency will occur. Therefore, it is considered that oxygen deficiency does not occur if the oxygen partial pressure exceeds a certain level.

When the powdered active material is used as a positive electrode active material or a negative electrode active material of a lithium secondary battery, the composition is uniform, the particle size is small, and the capacity is high even when charging and discharging at high current density. Almost no deterioration. Further, since there is no oxygen deficiency, there is almost no capacity deterioration due to repeated charge and discharge, and an excellent lithium secondary battery can be obtained.

As described above, according to the present invention, a spinel-type lithium-containing oxide having a uniform composition, a small particle size, and almost no capacity deterioration even during repeated charge / discharge with high current density, A powdery active material for a lithium secondary battery is obtained.

Next, as a second aspect of the present invention, a method for producing a powdery active material comprising a layered lithium-containing oxide is a method for producing a powdery active material for a lithium secondary battery. Then, a suspension obtained by suspending the raw material of the powdery active material in a flammable liquid, or an emulsion obtained by emulsifying a solution of the raw material of the powdery active material in a solvent in a flammable liquid, By spraying the droplets in an atmosphere containing oxygen and then burning the flammable liquid in the droplets to heat treat the droplets and react the raw materials in the droplets. A powdery active material for a lithium secondary battery, characterized by producing an oxide powder, and then reheating the oxide powder to 400 to 1000 ° C. to produce a powdery active material composed of a layered lithium-containing oxide. Method of manufacturing substance (hereinafter, 2 invention that) there is.

In the second aspect of the present invention, the most remarkable point is that, similarly to the first aspect of the present invention, after the droplet spraying and the heat treatment are performed, the oxide powder obtained by this is 400 to 1
Reheating to 000 ° C. to obtain a powdery active material composed of a layered lithium-containing oxide. Therefore, in this method, the suspension or emulsion preparation, droplet spraying, the flammable liquid in the droplets and their combustion,
The heat treatment of the droplets by the combustion heat and the reaction of the raw material in the droplets are the same as those described in the method of the first invention.

In this method, the oxide powder is first obtained by the reaction of the raw materials in the droplets. Therefore, the oxide powder is reheated to 400 to 1000 ° C. As a result, the oxide powder becomes a layered lithium-containing oxide and a powdered active material. When the reheating temperature is lower than 400 ° C., the layered lithium-containing oxide cannot be obtained because the temperature is low. On the other hand, when the temperature exceeds 1000 ° C., the crystal structure is disturbed by recrystallization, which causes a problem that the layered lithium-containing oxide is difficult to be generated.

The oxide powder may be reheated in the atmosphere. As a raw material for the powdery active material, Ni
When (nickel) is used, it is preferably performed in an oxygen gas atmosphere. Thereby, the layered lithium-containing oxide can be efficiently obtained.

Next, the function and effect of the second invention will be described. In the present invention, the above raw materials are mixed in the liquid state of suspension or emulsion. Therefore, the raw material can be completely homogenized. Since the homogenized droplets are sprayed and heated, the composition of the obtained powdery active material does not lose uniformity.

That is, the raw material instantly reacts in the droplets by the heat of the heat treatment to become an active material. On the other hand, when an emulsion is used, the solvent in the droplets evaporates as an unnecessary portion due to the heat during the heat treatment and is released to the outside of the reaction system. Therefore, the active material can have a uniform composition.

Further, the individual active material particles are individually formed for each droplet sprayed as described above. for that reason,
The active material is obtained as a powdery active material composed of primary particles of fine particles or secondary particles in which these particles are bonded (see FIG. 4). Further, the fine particles generated from the sprayed droplets have an average particle diameter of 0.01 to 10 μm.

Further, in the present invention, the heat treatment of the droplets is performed by burning a combustible liquid, and the droplet spraying is performed in an atmosphere containing oxygen.
Therefore, in the obtained layered lithium-containing oxide, oxygen deficiency does not occur, and an excellent powdery active material can be obtained. Thus, the reason why oxygen deficiency does not occur is presumed to be as follows. That is, the oxygen deficiency of the layered lithium-containing oxide is a function of temperature and oxygen partial pressure, and the higher the temperature and the lower the oxygen partial pressure, the more likely oxygen deficiency will occur. Therefore, it is considered that oxygen deficiency does not occur if the oxygen partial pressure exceeds a certain level.

When the powdery active material is used as a positive electrode active material or a negative electrode active material of a lithium secondary battery, the composition is uniform, the particle size is small, and the capacity is high even when charging and discharging at high current density. Almost no deterioration. Further, since there is no oxygen deficiency, there is almost no capacity deterioration due to repeated charge and discharge, and an excellent lithium secondary battery can be obtained. As described above, the present invention also has a uniform composition,
It is possible to obtain a powdery active material for a lithium secondary battery, which is composed of a layered lithium-containing oxide and has a small particle size and has almost no capacity deterioration even under repeated charge / discharge at high current density.

Next, as in the invention of claim 3, the raw material comprises a lithium compound and a metal or a metal compound,
The lithium compound is preferably one or more compounds of Li oxide, hydroxide, carbonate, nitrate, sulfate, acetate or oxalate. These are relatively easy to ionize in a solution and are excellent in uniformity.

Next, as in the invention of claim 4, the metal is Mn, Ni, Co, Ti, V, Al, Zn, Mo,
One or more metal elements of Cu, Fe, Cr, wherein the metal compound is a metal compound of oxides, hydroxides, carbonates, nitrates, sulfates, acetates, and oxalates of the above metals. It is preferably one or more metals or metal compounds. These are relatively easy to ionize in solution and are excellent in improving uniformity.

Among the above metals, Mn, Ti and V
Is most suitable for producing a powdery active material composed of a spinel-type lithium-containing oxide according to the first invention.
On the other hand, among the above metals, Mn, Ni, Co, V, Al, Z
n, Mo, Cu, Fe, and Cr are optimal when the powdery active material made of the layered lithium-containing oxide is produced according to the second invention.

Next, as in the invention of claim 5, as the solvent, one or more of water, an acid aqueous solution, an alkaline aqueous solution, and an organic solvent are used.

In addition, the heat treatment of the droplets is performed in the range of 300 to 1
It is preferable to carry out in a heating atmosphere of 200 ° C.
If the temperature is less than 300 ° C, the heat treatment is insufficient, while 120
If the temperature exceeds 0 ° C, there is a problem such that stable operation of the device becomes difficult.

In any of the above methods, a minute amount of additive such as Br, Mg, Zn, Nb, Sn, Sb may be added to the powdery active material in order to improve cycle characteristics. . The method of the present invention, as described above,
Since the raw material of the powdered active material and the suspension or emulsion are used, it is very easy to mix the trace amount of the additive. The lithium secondary battery capable of utilizing the powdery active material obtained by the present invention may have a non-aqueous electrolyte or an aqueous electrolyte, but especially the one using a non-aqueous electrolyte has excellent battery characteristics. Is desirable and desirable.

[0041]

BEST MODE FOR CARRYING OUT THE INVENTION

Embodiment 1 A method for manufacturing a powdery active material for a lithium secondary battery according to an embodiment of the first invention will be described with reference to FIG. 1 together with an apparatus for carrying out the manufacturing method. That is, in the method for producing a powdery active material in this example, as shown in the figure, first, a suspension 1 in which a raw material of a powdery active material is suspended in a combustible liquid is used together with an oxygen-containing gas 2 from an atomizer 31 to a reactor. 3 is sprayed as droplets 15.

Then, in the reactor 3, the flammable liquid is burned to heat the droplets 15. By this heat treatment, the raw material in the droplet 15 is reacted and the solvent in the droplet is evaporated to produce the powdery active material 4 made of spinel type lithium-containing oxide.
The powdery active material 4 is settled and collected in the collector 36.

That is, the above-mentioned manufacturing apparatus comprises a cylindrical reactor 3, and the suspension 3 in the tank 10 in the reactor 3.
(Or emulsion, in the present example, the same applies hereinafter). The reactor 3 includes a reaction passage (combustion part) 35, an atomizer 31 for spraying the suspension into the reaction passage 35, a burner 32 for heating the sprayed suspension 1, and a collected powdered active material. And a powder collector 36 for removing the powder.

In the above production, the atomizer 31
The oxygen-containing gas 2 using air and the suspension 1
Is supplied. From the atomizer 31, the suspension 1 is sprayed into the reaction passage 35 together with the oxygen-containing gas 2 to form droplets 15. The combustible liquid in the suspension 1 is ignited and burned by the burner 13 arranged in the reaction passage 35 to generate the powdery active material 4 for the lithium secondary battery. The powdery active material 4 is collected by the powder collector 36 located at the bottom of the reactor 3. The exhaust gas 37 generated together with the generation of the powdered active material 4 is discharged to the outside of the reactor 3 via the powder collector 36.

According to the present example, the raw material of the powdery active material is made into a suspension together with the flammable liquid, and the suspension is sprayed to form liquid droplets, and the solution reaction is carried out in the reactor 3. Therefore, the raw material instantly reacts in the droplet due to the heat of combustion of the flammable liquid to become an active material.

On the other hand, the solvent in the droplets is promptly released from the reaction system. Therefore, the active material has a uniform composition.
In addition, individual active material particles are formed for each sprayed droplet. Therefore, the active material is obtained as a powdery active material composed of primary particles and secondary particles of fine particles.

Further, since the heat treatment of the droplets is performed by burning a combustible liquid and the droplets are sprayed together with the oxygen-containing gas, the powdery active material which is the spinel-type lithium-containing oxide contains oxygen. No loss occurs. When the powdered active material is used as a positive electrode diffusion plate or a negative electrode diffusion plate, the composition is uniform, the particle size is small, and there is no oxygen deficiency. Therefore, it is possible to construct an excellent lithium secondary battery that has almost no capacity deterioration even at high current density charge / discharge.

Embodiment 2 This example is a specific example in which a lithium secondary battery was manufactured by using the powdery active material obtained by the present invention and a charge / discharge test was conducted. Indicate. First, the powdery active material was manufactured as the positive electrode active material by the apparatus described in the first embodiment as follows.

That is, LiNO ₃ (lithium nitrate) and M
_{n (NO 3) 2 · 6H} 2 O mole (manganese nitrate hexahydrate) ratio of 1: in a mixture with 2, added emulsifiers sorbitan monolaurate, suspended in kerosene as flammable liquids , An emulsion was prepared. This emulsion was sprayed from the atomizer 31 to the reaction passage 35 by the metering pump 11 of the above apparatus and the oxygen-containing gas 2 was supplied.

The amount of oxygen-containing gas was adjusted so that the oxygen partial pressure was 20 to 30% when it was assumed that the combustible liquid was completely burned. At the same time, the burner 32 mixes the emulsion spray droplets and the oxygen-containing gas to 600 to 7
Burned at 00 ° C. Thus, the powder collector 36 collected the powdery active material of the spinel-type lithium-containing oxide made of LiMn ₂ O ₄ . The obtained powdery active material had a uniform particle size, with primary particles having a particle size of 0.1 μm or less forming secondary particles of about 2 μm.

The above heating temperature is obtained by monitoring the temperature of the wall surface of the reaction passage (combustion part) with a sheath thermocouple of φ3 mm, and the actual reaction temperature is estimated to be several hundreds higher than the above. Using the powdered active material obtained above,
Acetylene black was used as a conductive material, and PTFE was used as a binder to prepare a positive electrode. On the other hand, Li metal was prepared as the negative electrode active material.

The LiMn ₂ O ₄ positive electrode and Li
A lithium secondary battery was manufactured using a metal negative electrode. As non-aqueous electrolyte, PC (propylene carbonate) + D
ME (1.2 dimethoxyethane) was used, which contained LiClO ₄ as the electrolyte. A polypropylene film was used as the separator. A charge / discharge test was conducted on the lithium secondary battery. Charge / discharge conditions were a cut-off voltage of 3.5 to 4.5 V and a current density of 1.0 to 4.0 mA / cm ² .

As a comparative example, the above LiMn ₂ O ₄
Two types of comparative positive electrodes were produced using active material B in which the positive electrode was synthesized by the solid phase method and active material C in which the conventional spray pyrolysis method was synthesized. A lithium secondary battery was constructed in the same manner as above except for the above, and the same charge / discharge test was conducted. The above two types of active materials B and C were manufactured as follows.

That is, the active material B prepared by the solid phase method was prepared by mixing lithium nitrate and electrolytic manganese dioxide at 700.degree.
It was obtained by firing for 20 hours. Next, this LiMn
_{The 2} O ₄ active material was crushed, and otherwise the same as above, to prepare a positive electrode active material as a comparative example.

The active material C obtained by the conventional spray pyrolysis method was prepared by mixing lithium nitrate and manganese nitrate hexahydrate into an aqueous solution, which was sprayed with an ultrasonic vibrator to obtain 800 It was obtained by heating reaction at ℃. Next, this LiMn ₂ O ₄ active material powdered active material was manufactured in the same manner as above to form a positive electrode as a comparative example. Then, using the positive electrodes made of these active materials B and C, a lithium secondary battery was prepared in the same manner as above, and the same charge / discharge test as above was conducted.

The results of the above charge and discharge are shown in FIGS.
Figure 2 shows the relationship between the number of charge and discharge cycles and the discharge capacity,
On the other hand, FIG. 3 shows the relationship between the charge / discharge current density and the discharge capacity. In both figures, curve A is the discharge of the lithium secondary battery using the powdery active material obtained by the present invention, and curves B and C are the discharges of the lithium secondary battery using the active materials B and C obtained in the above comparative examples. The capacity (mAh / g) is shown.

It can be seen from FIG. 2 that the powdery active material of the method of the present invention has a high initial capacity and a small capacity deterioration of the lithium secondary battery even after repeated charge and discharge. Further, it can be seen from FIG. 3 that according to the powdery active material of the present invention, the capacity of the lithium secondary battery is hardly deteriorated even by charging / discharging at a high current density. On the other hand, according to the powdery active materials B and C according to the comparative example as the conventional method, it is found that the capacity deterioration occurs at an early stage due to the charge and discharge with a high current density.

The particle structure of the powdery active material obtained by the method of the present invention is a SEM photograph (magnification: 4000).
4 times) and this is shown in FIG. In addition, the lithium compound obtained by the solid-phase reaction method of the comparative example is shown in FIG.
In addition, FIG. 6 shows the lithium compound obtained by the conventional spray pyrolysis method.

As is known from FIG. 4, the powdery active material obtained by the method of the present invention has a uniform particle size of 0.1 μm or less,
It consists of spherical particles. On the other hand, it can be seen that the lithium compound obtained by the solid phase method of the above comparative example has a large rectangular plate shape as shown in FIG. As shown in FIG. 6, the lithium compound obtained by the spray pyrolysis method of the above comparative example has a spherical shape, but its particle size has a large variation (0.2%) as compared with the product of the present invention (FIG. 4). .About.3 .mu.m).

Embodiment 3 LiNO ₃ and Mn (NO ₃ ) ₂ .6H ₂ O were mixed at a molar ratio of 1: 2, and then an equal amount of distilled water was added to form an aqueous solution, which was used as a flammable liquid. An emulsion was prepared by emulsifying in kerosene. Using this emulsion, a powdered active material was obtained in the same manner as in Embodiment 2 above. Further, when a charge / discharge test was conducted in the same manner as in the second embodiment, the same characteristics as in the second embodiment were obtained.

Further, in the same manner as in the second embodiment, the SE
The morphology and particle size of the particles were confirmed by the M photograph. As a result, the powdery active material had a particle size of 0.
It was composed of fine particles of 1 μm or less and had a uniform particle size.

Embodiment 4 LiNO ₃ and MnO ₂ (electrolytic manganese oxide) were homogeneously mixed at a molar ratio of 1: 2 and then turbid in kerosene to prepare a suspension. Using this suspension, a powdery active material was obtained in the same manner as in Embodiment 2 above. Further, when a charge / discharge test was conducted in the same manner as in the second embodiment, the same characteristics as in the second embodiment were obtained. In addition, as in the second embodiment, the SEM
The morphology and particle size of the particles were confirmed by photographs. As a result, the powdery active material retained the particle size of MnO ₂ as a raw material and had a uniform particle size consisting of fine particles of 0.1 μm or less.

Comparative Experimental Example The amount of oxygen-containing gas was adjusted so that the oxygen partial pressure was 10% when it was assumed that the combustible liquid was completely combusted, and otherwise the powder was produced under the same conditions as in Embodiment 2 above. The active material was produced. Further, when a charge / discharge test was conducted in the same manner as in the second embodiment, the capacity was only about 70% of that in the second embodiment. The oxygen content of the above powdery active material was determined by inductively coupled plasma emission spectrometry and potassium permanganate titration, and LiMn ₂
An oxygen deficiency of O _3.91 was observed.

On the other hand, no oxygen deficiency was observed in the powdery active material of Example 2 above. Therefore, the capacity of the lithium secondary battery using the powdered active material of this Comparative Example deteriorated as described above because the oxygen deficiency was generated because the synthesis was not performed under an appropriate oxygen partial pressure. It is presumed that the cause is.

Embodiment 5 A powdery active material made of a layered lithium-containing oxide was manufactured using the apparatus shown in Embodiment 1, and a lithium secondary battery using this powdery active material was charged and discharged. A test was conducted (the same applies to Embodiments 6 to 8). 1 mol of Li nitrate /
Liter aqueous solution and 1 mol / liter aqueous solution of Ni nitrate were mixed 1: 1 to obtain 600 cc of mixed aqueous solution, 24 g of glycerin fatty acid ester as emulsifier and 400 cc of kerosene.
A stable emulsion was prepared by mixing with stirring.

A burner flame is formed by spraying and igniting this emulsion, and the flame temperature is measured at 900 ° C.
The oxide powder was synthesized under the conditions of. At this time, the oxygen excess amount in the reactor was adjusted to 10% by using a mixed gas of air and oxygen gas.

Then, the obtained black powder as the above oxide powder was heated to 700 ° C. to 1000 ° C. in an oxygen gas atmosphere.
And reheated for 2 hours each. Table 1 shows the diffraction peak intensity ratios of the crystal phase and the (003) plane and the (104) plane of the layered lithium-containing oxide obtained from the X-ray diffraction pattern after reheating.
Shown in In this example, the synthetic powder (oxide powder) before being reheated has a small amount of layered lithium-containing oxide, but is a powdery lithium-containing oxide having a layered structure developed by heating for a short time. An active material could be obtained.

Using the layered lithium-containing oxide having a reheating temperature of 900 ° C. obtained above, acetylene delac was used as the conductive material, and PTFE was used as the binding material to prepare a positive electrode. On the other hand, Li metal was prepared as the negative electrode active material. Then, a lithium secondary battery was produced using the LiNiO ₂ positive electrode and the Li metal negative electrode.

As the non-aqueous electrolyte, PC (propylene carbonate) + DME (1.2 dimethoxyethane) was used, and the electrolyte containing LiClO ₄ was used. A polypropylene film was used as the separator. A charge / discharge test was conducted on the lithium secondary battery. Charge / discharge conditions are cut-off voltage 2.7
～4.2V, was conducted at a current density 1.0~4.0mA / cm ^2. Table 2 shows the results of the charge / discharge measurement.

It can be seen from Table 2 that the powdery active material comprising the layered lithium-containing oxide of the present example has a high initial capacity and less capacity deterioration of the lithium secondary battery even after repeated charge and discharge. . Further, it can be seen that, according to the above powdery active material, the capacity of the lithium secondary battery is hardly deteriorated even by charging and discharging at a high current density.

[0071]

[Table 1]

[0072]

[Table 2]

Embodiment 6 A 1 mol / liter aqueous solution of Li nitrate and 1 of Ni nitrate
Mixed aqueous solution 6 in which a 1: 1 molar / liter aqueous solution is mixed
00cc is 24g of glycerin fatty acid ester as an emulsifier
And a kerosene 400 cc were mixed with stirring to form a stable emulsion. A burner flame was formed by spraying and igniting this emulsion, and an oxide powder was synthesized at a flame temperature measurement position of 900 ° C.

At this time, the oxygen excess amount in the reactor was adjusted to 25% by using a mixed gas of air and oxygen gas. Re-heating the obtained black powder as an oxide powder in an oxygen gas atmosphere at 900 ° C. for 2 hours to obtain a powdered active material composed of a layered lithium-containing oxide with a developed layered structure. I was able to.

Using the powdery active material obtained above, acetylene black was used as the conductive material, and P was used as the binder.
A positive electrode was produced using TFE. On the other hand, Li metal was prepared as the negative electrode active material. Then, the above LiNiO ₂
A lithium secondary battery was manufactured using a positive electrode and a Li metal negative electrode. PC + DME was used as the non-aqueous electrolyte, and LiCLO ₄ was used as the electrolyte. A polypropylene film was used as the separator.

A charge / discharge test was conducted on the above lithium secondary battery. Charge / discharge conditions include cut-off voltage of 2.7-
It was carried out at 4.2 V and a current density of 1.0 to 4.0 mA / cm ² . Table 3 shows the results of the charge / discharge measurement.

From Table 3, it can be seen that the powdery active material composed of the layered lithium-containing oxide of the present example has a high initial capacity and little capacity deterioration of the lithium secondary battery even after repeated charge and discharge. . Further, according to the powdery active material of this example, it is found that the capacity of the lithium secondary battery is hardly deteriorated even by charging and discharging at high current density.

[0078]

[Table 3]

Embodiment 7 A 1 mol / liter aqueous solution of Li nitrate and 1 of Co nitrate
Mixed aqueous solution 6 in which a 1: 1 molar / liter aqueous solution is mixed
00cc is 24g of glycerin fatty acid ester as an emulsifier
And a kerosene 400 cc were mixed with stirring to form a stable emulsion. A burner flame was formed by spraying and igniting this emulsion, and an oxide powder was synthesized at a flame temperature measurement position of 900 ° C.

At this time, the oxygen excess amount in the reactor was adjusted to 10% by using a mixed gas of air and oxygen gas. By reheating the obtained black powder as an oxide powder in an oxygen gas atmosphere at 800 ° C. for 2 hours, a powdery active material composed of a lithium-containing oxide having a developed layered structure could be obtained. . Using the powdered active material obtained above, acetylene black was used as the conductive material, and PTFE was used as the binding material to prepare a positive electrode. On the other hand, Li metal was prepared as the negative electrode active material.

Then, a lithium secondary battery was prepared using the LiCoO ₂ positive electrode and the Li metal negative electrode. PC + DME was used as the non-aqueous electrolyte, and Li was used as the electrolyte.
The one containing ClO ₄ was used. A polypropylene film was used as the separator.

A charge / discharge test was conducted on the lithium secondary battery. Charge / discharge conditions include cut-off voltage of 2.7-
The test was performed at 4.2 V and a current density of 1.0 to 4.0 mA / cm ² . Table 4 shows the result of the charge / discharge measurement. From Table 4, it can be seen that the powdery active material composed of the layered lithium-containing oxide of the present example has a high initial capacity and less capacity deterioration of the lithium secondary battery even after repeated charge and discharge. Further, according to the powdery active material of this example, it is found that the capacity of the lithium secondary battery is hardly deteriorated even by charging and discharging at high current density.

[0083]

[Table 4]

Embodiment 8 A 1 mol / liter aqueous solution of Li nitrate and NiO were mixed with Li
Suspension 6 in which the molar ratio of Ni and Ni was 1: 1
00cc is 24g of glycerin fatty acid ester as an emulsifier
And a kerosene 400 cc were mixed with stirring to prepare a suspension. A burner flame is formed by spraying and igniting this suspension, and the burner flame is detected at the flame temperature measurement position.
Oxide powder was synthesized under the condition of 00 ° C.

At this time, the oxygen excess amount in the reactor was adjusted to 25% by using a mixed gas of air and oxygen gas. By reheating the obtained black powder as an oxide powder in an oxygen gas atmosphere at 900 ° C. for 2 hours, a powdery active material composed of a lithium-containing oxide having a developed layered structure could be obtained. . Using the powdered active material obtained above, acetylene black was used as the conductive material, and PTFE was used as the binding material to prepare a positive electrode. On the other hand, Li metal was prepared as the negative electrode active material.

Then, a lithium secondary battery was prepared using the LiNiO ₂ positive electrode and the Li metal negative electrode. PC + DME was used as the non-aqueous electrolyte, and Li was used as the electrolyte.
The one containing CLO ₄ was used. A polypropylene film was used as the separator. A charge / discharge test was conducted on the lithium secondary battery. Charge / discharge conditions were a cut-off voltage of 2.7 to 4.2 V and a current density of 1.0 to 4.0 mA / cm ² . Table 5 shows the result of the charge / discharge measurement.

From Table 5, it can be seen that the powdery active material composed of the layered lithium-containing oxide of this example has a high initial capacity and less capacity deterioration of the lithium secondary battery even after repeated charge and discharge. Further, according to the powdery active material of this example, it is found that the capacity of the lithium secondary battery is hardly deteriorated even by charging and discharging at high current density.

[0088]

[Table 5]

[0089]

EFFECTS OF THE INVENTION According to the present invention, a spinel type or a layered type having a uniform composition, a small particle size, no oxygen deficiency, and almost no capacity deterioration even during repeated charge / discharge with high current density. It is possible to provide a method for producing a powdery active material for a lithium secondary battery, the method comprising a lithium-containing oxide of a type.

[Brief description of drawings]

FIG. 1 is an explanatory diagram of a manufacturing apparatus for performing a method for manufacturing a powdered active material according to the first embodiment.

FIG. 2 is a diagram showing the relationship between the number of cycles and the discharge capacity during charge / discharge of the second embodiment.

FIG. 3 is a diagram showing the relationship between the charge / discharge current density and the discharge capacity during charge / discharge of the second embodiment.

FIG. 4 is a photograph as a substitute for a drawing (magnification: 400, showing the particle structure of the powdery active material obtained by the method of the present invention in Embodiment 2.
0 times).

5 is a drawing-substitute photograph (magnification: 4000 times) showing a particle structure of an active material obtained by a solid-phase reaction method as a comparative example method in Embodiment 2. FIG.

6 is a drawing-substitute photograph (magnification: 4000 times) showing a particle structure of an active material obtained by a thermal decomposition method as a comparative example method in Embodiment 2. FIG.

[Explanation of symbols]

 1. . . Suspension, 11. . . Metering pump, 15. . . Droplet, 2. . . Oxygen-containing gas, 3. . . Reactor, 31. . . Atomizer, 35. . . Reaction passage, 36. . . Powder collector, 4. . . Powdered active material,

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Masahiko Kato 1 Wanowari, Arao-cho, Tokai-shi, Aichi Aichi Steel Co., Ltd. (72) Akihiko Murakami 1 Wano-wari, Arao-cho, Tokai-shi, Aichi Aichi Steel Incorporated (72) Inventor Kazuma Takatori 1 in No. 41 Yokomichi, Nagakute-cho, Aichi-gun, Aichi-gun, Toyota Central Research Institute, Inc. (72) Inventor Naoyoshi Watanabe 41, Nagakute, Nagakute-machi, Aichi-gun, Aichi Address # 1 Toyota Central Research Institute Co., Ltd. (72) Inventor Toshihiko Tani 41, Nagakute-cho, Aichi-gun, Nagakute-cho Ai-ken, Toyota Central Research Institute Inc. (72) Inventor Gen Sasaki Nagakute, Aichi-gun, Aichi Prefecture No. 41, Yokomichi, Chozai, Kyoto, Japan

Claims (5)

[Claims] 1. A method for producing a powdery active material for a lithium secondary battery, comprising: a suspension in which a raw material of the powdery active material is suspended in a flammable liquid; or a raw material of the powdery active material. An emulsion obtained by emulsifying a solution prepared by dissolving in a solvent in a flammable liquid is sprayed in the form of droplets in an atmosphere containing oxygen, and then the flammable liquid in the droplets is burned. A powdery active material for a lithium secondary battery, characterized in that the powdery active material made of spinel-type lithium-containing oxide is produced by heating the liquid droplets and reacting the raw materials in the liquid droplets. Manufacturing method. 2. A method for producing a powdery active material for a lithium secondary battery, comprising: a suspension in which a raw material of the powdery active material is suspended in a flammable liquid; or a raw material of the powdery active material. An emulsion obtained by emulsifying a solution prepared by dissolving in a solvent in a flammable liquid is sprayed in the form of droplets in an atmosphere containing oxygen, and then the flammable liquid in the droplets is burned. , Heating the droplets to react the raw materials in the droplets to form an oxide powder,
Then, the oxide powder is reheated to 400 to 1000 ° C. to produce a powdery active material composed of a layered lithium-containing oxide, a method for producing a powdery active material for a lithium secondary battery. 3. The material according to claim 1, wherein the raw material comprises a lithium compound and a metal or a metal compound, and the lithium compound is an oxide, hydroxide, carbonate, nitrate, sulfate or acetate of Li. Alternatively, a method for producing a powdery active material for a lithium secondary battery, which is one or more compounds of oxalate. 4. The metal according to claim 3, wherein the metal is Mn,
Ni, Co, Ti, V, Al, Zn, Mo, Cu, F
e, Cr, which is one or more metal elements, and the metal compound is one of the metal oxides, hydroxides, carbonates, nitrates, sulfates, acetates, and oxalates of the above metal elements. 1. A method for producing a powdery active material for a lithium secondary battery, comprising: 5. The method according to claim 1, wherein:
The method for producing a powdery active material for a lithium secondary battery, wherein the solvent is one or more of water, an acid aqueous solution, an alkaline aqueous solution, and an organic solvent.